The present invention relates to the field of surgical clips generally, and, in particular, to the field of surgical clips formed of a shape memory alloy.
Several methods are known in the art for joining portions of hollow organs, such as the gastrointestinal tract. These include threads for manual suturing, staplers for mechanical suturing, and compression rings and clips.
While manual suturing is universally known and relatively inexpensive, the degree of success depends considerably on the skill of the surgeon. Another disadvantage is that post-operative complications are common. Further, suturing an organ results in lack of smoothness of the tissue therein, which, when the sutured organ is part of the gastrointestinal tract, hampers peristalsis in the sutured area. Finally, suturing is both labor and time consuming.
Staplers for mechanical suturing ensure a reliable joining of tissue and enable the time needed for surgery to be reduced, compared with manual suturing. However, due to the facts that such staples are not reusable and that a great many types and sizes are required, the price of staples is high. Also, after healing, metal staples remain in place along the perimeter of the which reduces elasticity of the junction and adversely affects peristalsis when the sutured organ is part of the gastrointestinal tract.
Junctions using compression devices such as rings and clips ensure the best seal and post-operative functioning of the organs. Two types of compression devices are known, namely, rings made of resorption plastics and clips made of memory alloys. Plastic rings are cumbersome and expensive. Also, the compression force is applied only momentarily at the junction and is reduced as the tissue is crushed. Clips made of shape memory alloys enable portions of tissue to be pressed together when equilibrium with body temperature is reached, whereat, due to the inherent properties of the alloys, the clips resume their memorized shape.
Development of clips made of memory alloy materials has increased recently, as they have many advantages over other devices. Their design is simple, they are cheap, they are small in size and possess universal qualities, and they are self-evacuated from the gastrointestinal tract.
It is known in the art to provide a surgical fastening clip which applies a clamping force to a site, such as a blood vessel, thereby reducing its cross-sectional area. It is also known to provide a surgical fastening clip formed of a shape memory alloy which deforms to a closed configuration when heated, such that the clamping force applied thereby is increased as it is heated. For example, U.S. Pat. No. 5,171,252 discloses a surgical fastening clip formed of a shape memory alloy; the device disclosed therein includes separate legs which close tightly around a site. Such a device is limited in its uses, such as for clamping blood vessels, and is not suitable for joining portions of the gastrointestinal tract.
EP 0,326,757 discloses a device for anastomosing a digestive tract, which includes a plurality of U-shaped retaining clips disposed around a soluble support tube. The tube is positioned inside portions of the digestive tract to be joined, and includes an outer groove around which are disposed the U-shaped retaining clips. The retaining clips are made of a shape memory alloy such that the open ends thereof close at a predetermined temperature, thus joining ends of the digestive tract. Once the ends of the digestive tract have been joined, the tube is dissolved. Such a device is disadvantageous in that its use requires that a plurality of clips to be properly positioned simultaneously. Also, there is no assurance that the resulting junction will be smooth, due to the plurality of sites of the digestive tract joined by the plurality of clips.
SU 1,186,199 discloses a memory alloy clip consisting of two parallel coils to be used for joining portions of a hollow organ, such as an organ of the gastrointestinal tract. The portions of the organ to be joined are aligned, and each of the plastic coils is introduced through a puncture formed in the wall of one of the portions. The coils are positioned such that, when heated, they compress the aligned walls therebetween, thus maintaining the portions of the walls held within the loops of the coils adjacent each other. Thereafter, incisions are made through the portions of the walls held within the loops of the coils, such that a passageway is created between the two organ portions. The punctures in the organ walls must then be surgically sewn closed with interrupted surgical sutures.
A major disadvantage of known memory alloy clips is that they permit compression of only approximately 80-85% of the junction perimeter, thus requiring additional manual sutures, which reduce the seal of the junction during the healing period and its elasticity during the post-operative period. Also, this additional suturing is problematic inasmuch as it has to carried out across a joint which includes a portion of the clip, thereby rendering difficult the sealing and anastomosis of the organ portions. Furthermore, once in place, clips according to the prior art require further surgery to be performed, namely, incisions through tissue so as to create a passageway between the two organ portions which have been joined by the clip.
There is thus a need for a surgical device which facilitates compression of substantially the entire perimeter of the junction between the organ portions being joined, which would obviate the need for additional manual sutures and which ensure the smooth seal of the junction during the healing period and its elasticity during the post-operative period. Additionally, there is a need for a surgical device which, once in place, would enable a passageway to be created between the two organ portions which have been joined together, without requiring further surgery to be performed on the organ.
The present invention seeks to provide an improved surgical clip formed of a shape memory alloy, and a method of joining two portions of a hollow organ, which overcome disadvantages of prior art.
There is thus provided, in accordance with a preferred embodiment of the present invention, a surgical clip formed at least partly of a shape memory alloy, the clip including: a first length of a wire defining a closed geometrical shape having a central opening; a second length of a wire defining a closed geometrical shape similar in configuration and magnitude to that of the first length of wire, wherein, when placed in side-by-side registration, the first and second lengths of wire fully overlap; an intermediate portion located between the first length of wire and the second length of wire, the intermediate portion formed of a shape memory alloy; a cutting element associated with the first length of wire; a counter element associated with the second length of wire and arranged for cutting engagement with the cutting element; wherein when at a first temperature or higher, the first and second lengths of wire are positioned in a side-by-side closed position and the shape memory alloy is in an elastic state, and further, when at a second temperature or lower, below the first temperature, the shape memory alloy is in a plastic state, thereby enabling the first and second lengths of wire to be moved into and to retain a spaced apart position, and upon heating of the clip to a temperature at least equal to the first temperature, the first and second lengths of wire return to the side-by-side closed position, thereby to apply a compressive force to tissue located therebetween.
Additionally in accordance with a first embodiment of the present invention, the surgical clip further includes apparatus for pressing the cutting element into cutting engagement with the counter element wherein, when at the first temperature or higher, the apparatus for pressing presses the cutting element into cutting engagement with the counter element.
In accordance with an alternative embodiment of the present invention, the surgical clip further includes apparatus for pressing the cutting element into cutting engagement with the counter element wherein, when at the first temperature or higher, the apparatus for pressing is actuatable by an outside force.
Further in accordance with an embodiment of the present invention, the geometrical shape of the surgical clip is a circle.
Yet further in accordance with an alternative embodiment of the present invention, the geometrical shape of the surgical clip is an ellipse.
In accordance with an embodiment of the present invention, the first length of wire and the second length of wire are defined by a continuous coil.
Still further in accordance with an alternative embodiment of the present invention, the first length of wire and the second length of wire are two distinct lengths of wire, each defining a closed geometrical shape.
Still further in accordance with a preferred embodiment of the present invention the counter element also includes a cutting element.
According to the present invention, there is also provided a method for anastomosing a gastrointestinal tract, the method including the following steps: (a) providing a surgical clip formed at least partly of a shape memory alloy, the clip including: a first length of a wire defining a closed geometrical shape having a central opening; a second length of a wire defining a closed geometrical shape similar in configuration and magnitude to that of the first length of wire, wherein, when placed in side-by-side registration, the first and second lengths of wire fully overlap; an intermediate portion located between the first length of wire and the second length of wire, the intermediate portion formed of a shape memory alloy; a cutting element associated with the first length of wire; a counter element associated with the second length of wire and arranged for cutting engagement with the cutting element; (b) cooling at least the intermediate portion to a temperature below a lower phase transition temperature thereof, whereat the intermediate portion is in a plastic state, thereby enabling the first and second lengths of wire to be moved into and to retain a spaced apart position; (c) manually moving apart the first and second lengths of wire; (d) drawing together portions of the gastrointestinal tract wherein anastomosis is desired, such that the portions are in adjacent, side-by-side relationship, at least one of the portions being open-ended; (e) surgically sealing the open ends of the portions of the gastrointestinal tract; (f) forming punctures in walls of the gastrointestinal tract adjacent to each other, the puncture being adjacent; (g) introducing the clip through the punctures, such that the a wall of each portion of the gastrointestinal tract is situated between the first and second lengths of wire; (h) maintaining the relative positions of the portions of the gastrointestinal tract and the clip in relation thereto, while raising the temperature of at least the intermediate portion to a temperature above its upper phase transition temperature, whereat the intermediate portion is in an elastic state, thereby causing the first and second lengths of wire to attain the side-by-side registration, thereby to apply a compressive force to tissue located therebetween.
Additionally in accordance with a preferred embodiment of the present invention, according to the method, in step (h), the temperature of the clip is raised to the temperature above its upper phase transition temperature by the heat of the gastrointestinal tract.
Further in accordance with a preferred embodiment of the present invention, according to the method, the clip further including apparatus for pressing the cutting element into cutting engagement with the counter element wherein, when at the upper phase transition temperature or higher, the apparatus for pressing presses the cutting element into cutting engagement with the counter element, thereby creating an opening in the tissue located between the first and second lengths of wire, thereby creating initial patency of the gastrointestinal tract; and the method includes after step (h), the additional step of widening the opening.